The invention relates to a physical model for demonstrating relief of pain, particularly referred pain, in the craniofacial region.
Physical models are helpful to simulate the cause and effect of various orthopedic and neuromuscular processes. Abnormalities in these processes often result in pain. Because of the complex physical and physiological relationships among the vascular, neuromuscular, and orthopedic systems, models are useful to locate and visualize the intricate interplay among these systems in an attempt to correct the abnormality and thus relieve the pain.
Models are particularly useful to demonstrate relationships in the craniofacial and upper body areas, where structures are more compact and the interdependence of these structures is more readily visualized. For example, craniofacial muscle stress is a result of changes in torque or force vectors in the muscles and ligaments between the jaw and cranium. An example of one such muscle that may be stressed is the trapezius muscle. A stressed trapezius muscle refers pain to the head, leading to symptoms such as headache and joint pain. The trapezius muscle, located in the shoulder and neck and serving to support the head from the back, contains trigger points. Trigger points are one or more sites of irritable muscle tissue which are especially tender to squeezing or pressure. The trigger points usually cause the phenomenon of referred pain recognized at a position removed from their own location.
Referred pain is defined as pain in which an abnormality in a particular location results in pain being felt in a location distant from the source. The concept is complicated and is difficult for many individuals to comprehend. An example of referred pain is the pain in the left arm that is felt by an individual suffering a heart attack. While it is cardiac muscle (that is, the heart) that is deprived of oxygen, the pain is experienced in the arm. Less drastic muscle aggravation than that provoking a heart attack, for example skeletal muscle aggravation, can result from strenuous exercise, sudden movement, improper positioning for an extended duration, and so on. The aggravated muscles in one area of the body thus lead to muscle tension and pain in other areas of the body resulting from a complex series of elements, culminating in referred pain. If these elements can be relieved, the tension in muscles having trigger points will also be relieved and therefore will not refer pain to other areas of the body. The end result is that pain in other areas of the body, or referred pain, will be relieved.
Physical models of various body regions in general, and of the craniofacial region in particular, are well known. However, all suffer from the drawback that they do not demonstrate the phenomenon of referred pain. For example, U.S. Pat. No. 3,376,645 discloses a demonstration device that simulates proper and improper dental occlusion and its effect on the temporomandibular joint. The device includes bas-relief planar facsimiles of the human upper and lower jaws which are mounted on a planar support. The upper jaw is fixed while the lower jaw is removable and is adapted to pivot about the temporomandibular joint. By substituting alternative lower jaw facsimiles representing various malformations, including improper bite or occlusion, sliding or shifting of the lower jaw fore and aft can simulate the effect of the temporomandibular joint and muscles and ligaments in the face, head and neck.
Similarly, U.S. Pat. No. 3,616,537 discloses a demonstration device that includes upper and lower plates having representations of an upper and lower jaw and temporomandibular joint. The plates include slots and pins which may be adjusted to simulate different occlusions and their effect on the function of the temporomandibular joint.
As another example, U.S. Pat. No. 4,541,807 is a planar demonstration device similar to that disclosed in the aforementioned ""645 patent but including a series of rubber bands to simulate various muscles that support the lower jaw. The device also includes a series of replaceable inserts to represent different improper bites or occlusions, and which cause movement at the temporomandibular joint. Another series of inserts function to correct an improper bite or occlusion and to move the temporomandibular joint back to its proper position.
As still another example, U.S. Pat. No. 4,948,373 discloses a three-dimensional model of the human craniomandibular system. A cranium is pivotally mounted to the first cervical vertebra, and a series of rubber bands simulate various muscle functions. Insert or enlargement pieces may be added to or removed from the lower jaw to simulate Angle Class I, II and III situations. Inserts may also be used to simulate patients in which the lower jaw is either horizontal or parallel to the upper jaw, or is upwardly or downwardly inclined with respect to the upper jaw.
Each of these models fails to account for the common effects leading to referred pain. For example, one source of referred pain is pain triggered by a trigger point in the trapezius muscle which is tensed or aggravated due to the non-coincident central occlusion of the teeth and central relation of the temporomandibular joint. The cranium in each of these models is fixed and cannot pivot or tilt downwardly, thus the models do not take into account, and hence do not simulate, normal and abnormal trapezius muscle function. Although the ""373 patent uses rubber bands to simulate the effect of various muscles, it is a complicated three-dimensional device that does not account for the effects of coincident central relation and central occlusion, and furthermore does not show the effect of treatment of this problem. Because the concept of referred pain is difficult for many individuals to grasp, a visual model would be particularly useful in demonstrating the physiology underlying this complex phenomenon.
Muscles are cumulatively the largest single body organ and account for over forty percent of the body weight. Given the amount of stress and strain muscles endure, it is not surprising that many individuals suffer muscle pain. However, X-rays and other imaging techniques do not provide images of muscles. Thus, models demonstrating these complex relationships would have advantages in educating patients, physicians, therapists and other professionals who institute and monitor patient treatment, and in treating the patients who endure referred pain.
While a patient may not be able to grasp the complexities inherent in standard medical models, a model that clearly depicts the interrelatedness between abnormalities in craniofacial structures and sites of referred pain would facilitate a patient""s understanding and education. This, in turn, would likely motivate and assist a patient in taking corrective action to alleviate the problem. Such a model is therefore needed.
The invention includes a model of a human craniofacial region functional to demonstrate relief of referred pain. A head comprises a cranium that is pivotally joined to a neck supported on a base. A jaw is connected to the cranium at a joint that simulates the temporomandibular joint. Tensionable connectors, for example rubber bands or springs, represent muscles such as the trapezius muscle and jaw muscle. Tension can be varied in these connectors to demonstrate effects between the positions of the cranium, jaw and muscles that can result in pain. The model also contains teeth and can demonstrate the teeth and temporomandibular joint in various positions. The model may be a physical model and may also include a device such as a splint inserted between the teeth to demonstrate how pain may be relieved.
The invention also includes a method for physically demonstrating a source of pain, particularly referred pain. A model is provided of a human cranium hinged to a base and a jaw jointed to the cranium to simulate the temporomandibular joint, containing teeth, and having tensionable connectors representing a state of muscle tension. The method includes varying the position of the head and teeth, varying the tension on the connectors, and/or inserting a splint to demonstrate the effect of jaw position and trapezius irritation as a source of pain, and the relief thereof.
There is thus briefly summarized a craniofacial model that is both easy to use and easy to understand, and methods of using the model to demonstrate the effect of source and relief of pain involving these structures. The invention will be further appreciated in light of the following drawings and detailed description.